Dental caries (tooth decay) is the most prevalent infectious disease afflicting American Public. Biofilm formation is crucial for the pathogenesis of dental caries caused by cariogenic bacterium Streptococcus mutans. S. mutans has adapted to the biofilm lifestyle. Bacteria within a biofilm are extremely (100-1000 fold more) resistant to traditional antibiotics; therefore development of new classes of anti-biofilm reagents with the ability to inhibit biofilm formation by S. mutans is necessary and critical for the treatment and prevention of dental caries. The most potent and versatile class of molecules with anti-biofilm properties are those derived from the 2-aminoimidazole (2-AI) scaffold discovered by the Melander group from natural marine products. The 2-AI derivative is capable of inhibiting and dispersing diverse biofilms formed by Gram-negative and Gram-positive bacteria. Given the success of this 2-AI derivative, we have become interested in designing, screening and characterizing its derivatives that will both inhibit and disperse S. mutans biofilms with the caveat that the small molecule compounds will not affect biofilm formation by commensal streptococci. We will use Streptococcus sanguinis and Streptococcus gordonii as model commensal streptococci as both are primary colonizers of the tooth surface and numerically dominated in the healthy oral cavity. Our preliminary studies have shown that modification of 2-AI can enhance selectivity of the 2-AI derivatives, and we have derived a 2-AI analogue that exhibits moderate selectivity towards inhibiting S. mutans. The goal of our current proposal is to develop new small molecule-based therapeutics. We hypothesize that 2-AI derivative can be used as a scaffold to design advanced analogues that: are more selective and potent towards inhibiting S. mutans. Three specific aims are proposed to achieve the goal: Specific Aim 1: Synthesize and screen diverse libraries of 2-AI derivatives to identify compounds with selective anticariogenic biofilm activity. Specific Aim 2: Determine efficacy of the lead small molecules in an animal model of dental caries. Specific Aim 3: Identify and characterize molecular targets of the potent small molecules and determine the underlying mechanism of the anticariogenic biofilm activity. A multidisciplinary research team among chemists, animal model experts, microbiologists and dentist scientists has been established to achieve the research goal. The close collaboration with Dr. Christian Melander, a pioneer in anti-biofilm synthetic chemistry to develop 2-AI derivatives, Dr. Sue Michalek, a leader in the caries research, and Dr. Noel Childers, a dentist scientist will facilitate the development of new anticariogenic biofilm compounds. This study will have a direct impact on the oral health of the public since the active compounds can be readily developed into an effective therapy that can be used routinely by the public.